BACTERIA AS THE CAUSES OF DISEASE. 77 



tion. He pointed out the different physiological characters 

 of organisms taken from different media, and showed that 

 different conditions were essential to the existence of different 

 organisms, and, in connection with a number of inoculation 

 experiments that they had carried on (with material sent 

 by him, which they allowed to undergo decomposition, 

 and by means of which rabbits were killed but no rods were 

 afterwards found in their blood), that they had produced no 

 anthrax because the incubation period was too short, because 

 the splenic enlargement was absent, because the animals 

 underwent much more rapid putrefaction, and because the 

 disease was capable of being transmitted to birds — a class 

 which up to that time had not been found to be susceptible 

 to this disease. During this controversy Davaine pointed out 

 that Pyasmia and Septicaemia could not be produced by the 

 inoculation of true anthrax virus. He described the bacteridia 

 of anthrax as totally devoid of movement in the blood, 

 and carefully distinguished between them and putrefactive 

 bacteria ; he demonstrated how these latter could, by their 

 presence and activity, diminish the activity of the anthrax 

 bacteria, and could in turn produce a septic condition, which 

 was in all essential respects absolutely different from splenic 

 fever. He demonstrated that these vibriones were vegetable 

 and not animal, and recognized the most important fact that 

 the environment, mode of nutrition, and products of excre- 

 tions of the anthrax micro-organism had a most marked 

 influence in modifying its activity and virulence. He did not 

 believe in the possibility of infecting the organism of the 

 foetus in utero, basing his belief on Brauell's and his own 

 experiments, and advanced the theory that the immunity 

 enjoyed by the foetus was due to the filtering action of the 

 placenta which, he contended, did not allow of the passage 

 of solid particles either from the maternal to the foetal 

 circulation or in the opposite direction. 



He concluded also that certain species of animals were 

 much more susceptible to the disease than others. He was 

 convinced at that time that malignant pustule, malignant 

 oedema and anthrax were all due to the presence of the same 

 organisms in animals or in man, and in fact he initiated the 

 whole theory of contagion from animals to man and vice 

 versd, and opened up the immense and fertile field of the 

 comparative pathology of infective diseases. In 1868 he 



